Tuesday, 28 February 2012

Creating the Hair ... the final attempt?

 Hair - Method 2

After doing some further research on hair and a few trial and error tests I now had to re-create the hair but keeping the dynamics in mind. (Hoping I will stick to this method and not change it again)

Just like before I created the unwrapped scalp separately. Selected the scalp > Hair > Create Hair (U and V's set to 20, no randomization and using Paint FX)
I increased the hair clumping and the amount of hairs to get a more dense hair system.

The next step is very important for getting the dynamics correct. I shortened the length of the hair by using the Scale Hair Tool (This can also be done by painting 'Extend Hairs')

Before explaining what I did I think I should briefly explain the Start, Current and Rest Position.

Start Position: Position of the hair at the start frame of the simulation. The Start curves stick straight out when the hair is first created.

Rest Position: This is the position of the hair when no forces at acting upon it (Such as gravity) Setting the Rest position correctly can effect the shape of the hair and more importantly can act as a hairspray feature. For example if I create a fringe that falls to the left hand side, I can move the hair around, reacting with wind and gravity, and when the hair stops it will try to retain that original shape.

Current position: These are the output and/or Paint Effects curves generated by the hair system.This is how the hair behaves when you play the simulation, which includes built-in dynamics. Do not edit the Current Position; just view it.

So to set the rest position I styled the hair by selecting half of the curves and adding a Uniform Field. This is one way of moving the curves by the specific point you have selected (make sure to use a falloff in your selection) I then set the current and rest position from here.

Finally a few tweaks to the curves to get the hair flowing better. 
(This is something that might need further work. It's a long and tedious process.)

I will just show you what minor tweaks I did to the attributes to create the final hair.

 Left: Used a multistreak of 1 to create more dense hair without the increase of render time.

Right: Larger Multistreak spread

  Left:  Smaller multistreak spread.

Right: Thinner hair. 

  Left: More curl (more curl the less reaction to wind = easier for me to do)

Right: Production quality

  Left: Depth map shadows (Default)

Right: Depth map shadows (1024 size) Better result but still not great. Long in rendering time.
  Left: Raytraced shadows. Much nicer result.

Right: Raytraced with 'Light each hair' enabled. Didn't seem to change anything.

Finally to get the hair colliding with the head I had to create a sphere constraint (Trying to use a collision mesh with a polygon object doesn't seem to work) Before selecting the Collide Sphere I had to have the Hair Follicles selected. I created two, one for the head and one for the back of the neck. These are constrained to the hair system, which follows the scalp which is then constrained to the head mesh and then hidden.

The final outcome isn't perfect but I am happy with how far I have got. I intend to take this further by altering the positions of the follicles ... at the moment they seem to be too perfectly positioned around the head. I will also try to get the hair to either cast more shadows or just make it more dense (To get rid of the visible scalp) The main issue I am having with it at the moment is trying to export the whole system to another file.

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